1. Field of the Invention
The invention relates to a bearing shell for a crankshaft thrust bearing and more particularly to lubrication passageways for providing oil to axial bearing surfaces.
2. Background of the Invention
A bearing shell has been disclosed in U.S. Pat. No. 5,363,557. The known bearing shell is cylindrical and has two halves, separated along the axis of the bearing shell. The two semi-cylindrical bearing shell halves are arranged around a crankshaft and mounted in the engine block. Mounting takes place both in the radial direction—via the insides of the shell of the bearing shells—and in the axial direction—via the outer surfaces, directed axially outward, of the flanges. Axial forces may be exerted on the crankshaft by the engine and the transmission.
To reduce the friction between the bearing shell and the crankshaft, the corresponding bearing surfaces are lubricated with an oil film. In the bearing shell according to '557, oil is directed via a passage through the engine block to the inside of the bearing shell. An oil passage, for the distribution of oil, is provided circumferentially. Furthermore, the transition between the flanges and the shell are beveled, so that a clearance space of triangular cross section, via which oil can be distributed, is produced here between the bearing shell and the crankshaft. In this case, oil is forced from the circumferential oil passage through the radial bearing surface to the ends of the shell to reach the clearance spaces. According to '557, suitable recesses may be provided in the outer surfaces of the flanges to provide for further distribution of the oil via the axial bearing surface.
In practice, it has been found that, crankshaft thrust bearings according to prior art, are subject to high wear due to thrust forces occurring in certain situations or in certain vehicle types. This high wear leads to rapid destruction of the bearing.